Pitch diameter rounder



April 1970 R. w. ANTHONY ETAL 3,505,847

PITCH DIAMETER ROUNDER Filed Aug. 10, 1967 INVENTORS SEL W. ANTHONY I I H. MOTZ ATTORNEYS United States Patent O 3,505,847 PITCH DIAMETER ROUNDER Russel W. Anthony and Carl H. Motz, Detroit, Mich., assignors, by niesne assignments, to Lear Siegler, Inc., Santa Monica, Calif., a corporation of Delaware Continuation-impart of application Ser. No. 465,487, June 21, 1967. This application Aug. 10, 1967, Ser. No. 659,672

Int. Cl. B21b N08 US. Cl. 72-107 1 Claim ABSTRACT OF THE DISCLOSURE Method and apparatus for rounding an internally toothed gear in which the gear is supported on a pair of rotary members located within the gear, one of which is a pinion and the other of which is a smooth roller, and in which the ring deforming pressure is applied by a pair of external rollers located at a fixed center distance, the

rollrs being moved generally tangentially with the rollers contacting the outer surface of the gear at points spaced substantially 90 degrees from the zone of engagement with the internal members, and in which the direction of movement of the rollers over the gear is such as to apply increased pressure between the smooth internal roller and the gear.

CROSS-REFERENCE TO RELATED APPLICATION [his is a continuation-in-part of application Ser. No. 465,487, filed June 21, 1965, now Patent 3,353,392.

SUMMARY OF THE INVENTION In accordance with the present invention, an internally toothed gear is supported on a pair of rotary members located at the inner surface of the gear. One of the members is in the form of a pinion in tight mesh with the gear. The other rotary is in the form of a smooth surfaced cylindrical roller. Ring deforming pressure is applied to the outer surface of the gear by a pair of rollers located at a fixed center distance and adapted to be moved generally tangentially over the gear with the zones of contact between the external rollers located approximately-90 degrees from the zones of contact between the gear and the internal rotary members. With this arrangement the forces developed between the external rollers and the gear tending to displace the gear in a direction perpendicular to its axis, are balanced by the forces developed between the smooth surfaced roller and the crests of the teeth of the gear. The internal pinion applies sutficient pressure to the teeth of the gear to perform a burnishing action and to remove or substantially reduce nicks and burrs. The ring rounding operation takes place subsequent to heat treatment of the work gear.

Details and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing, illustrating a preferred embodiment of the invention.

; BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a diagrammaticview illustrating the relationship between the operating parts.

FIGURE 2 is an enlarged transverse sectional view showing the support for the rotary members.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing there is illustrated a gear G having a smooth cylindrical exterior surface 10 and a toothed interior surface 12. The gear is illustrated as supported by a pair of internal members, specifically, a roller 14 having a smooth exterior surface, and a pinion 16 having teeth conjugate to the teeth of the gear G. Means are provided for effecting relative approach and separation between the members 14 and 16 and to apply sufficient pressure to cause the teeth of the pinion 16 to perform a burnishing or nick and burr removing operation on the teeth of the gear.

The present invention differs from the subject matter of prior Patent 3,353,392 primarily in the use of the smooth surfaced roller 14, and in view of this, a further difference resides in the elimination of a timing gear which was employed within the gear to be rounded in mesh with the teeth of two internal pinions.

In the present case, suitable means (not shown) are connected to the pinion 16 for driving the pinion in rotation and thus effecting rotary movement of the gear G about its axis.

Means are provided for effecting a distortion or flattening of the gear G beyond its elastic limit and this means comprises a carrier 20 having rollers 22 engageable with the outside cylindrical surface of the gear G. The rollers 22 are set apart a distance slightly less than the normal outside diameter of the gear G so that when the rollers 22 engage the outer surface of the gear at diametrically opposite points as illustrated, the gear is distorted somewhat beyond its elastic limit.

Means are provided for advancing the carrier 20 downwardly with the parts in the relationship illustrated in the figure, and this means comprises a fixed support 24 which is internally threaded and receives a screw 26 connected to a plate 28.which in turn is fixedly mounted on the carrier 20. The screw 26 is rotated by suitable means such for example as a hand wheel 30.

The operation is substantially the same as in prior application Ser. No. 465,487, in that the gear G is rotated at least once and preferably a plurality of times while it is distorted by the rollers 22, and thereafter the rollers are gradually withdrawn while the gear is continuously rotated by the pinion 16.

Downward movement of the rollers '22 from a clearance position above the gear to the illustrated position develops a substantially downward thrust on the gear G and for this reason it is desired to counterbalance this thrust with the smooth surfaced roller 14 which operates against the crests of the teeth of the gear G. It will be understood that the operation is feasible because the teeth of the gear G are helical so that a smooth rolling action takes place with the smooth surfaced roller 14.

. Referring now to FIGURE 2 there is illustrated means for supporting the rotary members 14 and 16. This means comprises a stationary pivot support 30 to which arms 32 and 34 are pivoted. Arm 32 carries a shaft 36 adapted to support the rotary member 14, and arm 34 carries a. shaft 38 adapted to support the pinion 16. The movable ends of the arms 32 and 34 are provided with hardened wear buttons 40 engaging the opposite sides of a rotary cam 42. Movement of the rotary members 14 and 16 toward and away from each other is accomplished by rotating the cam 42, a tension spring 44 being provided to maintain the buttons 40 in engagement with the cam 42.

The'drawing and the foregoing specification constitute a description of the improved pitch diameter rounder in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claim.

What we claim as our invention is:

1. Apparatus for rounding internal gears which comprises a pair of independently rotatable rotary members adapted to support an internal gear and to engage its inner surface at points substantially degrees apart, one of said members being a pinion adapted to mesh with the gear and the other one of said members being a smooth surfaced roll engageable with the tops of the teeth of the internal gear, means for forcing said members apart to apply a predetermined pressure between the teeth of the pinion and gear, means for driving the pinion in rotation, a pair of spaced rolls, a carrier for said rolls, means for moving said carrier in a direction to move said rolls generally tangentially of the gear into a position in which they engage the gear at diametrically opposite zones substantially 90 degrees from the zone of engagement between the gear and said members, said pair of rolls being spaced apart a distance such as to distort the gear beyond its elastic limit when thus engaged therewith, said smooth surfaced roll being positioned to sustain the lateral thrust on the gear occasioned by movement of said carrier to bring said pair of rolls into engagement with diametrically spaced zones on the outer surface of the gear.

References Cited UNITED STATES PATENTS 10 LOWELL A. LARSON, Primary Examiner US. Cl. X.R. 72 -110 

